This invention relates to a pressure piston for a die-casting machine having a carrier passing axially through it, which carrier has a central blind bore, issuing from the piston side lying opposite to the piston end pressure surface and leading to the piston crown, for piston cooling, and having a detachable piston skirt the outer peripheral surface of which, at least over a part of its axial extent, forms a piston working surface, the piston skirt preferably being of a beryllium-copper alloy, the skirt being radially centered on the carrier and enclosing the latter with formation of an outwardly closed-off annular cooling medium space which, for piston cooling, is in communication through transverse passages serving for inflow and outflow with the blind bore. The arrangement is made so that the blind bore has in the piston crown a bore section of smaller diameter, into which there enters a cooling medium supply pipe contained in the piston rod carrying the piston, that the transverse passages are arranged on the opposite ends of the annular cooling medium space and the transverse passage allocated to the piston crown opens into the bore section, that the carrier itself forms the entire piston crown, which is formed as piston pressure surface and as radially protruding abutment ring, and that the carrier has a clamping sleeve screwable on to it and the piston skirt is firmly braced in the axial and radial directions with the carrier between abutment ring and clamping sleeve.
Such a pressure piston is relatively simple in construction and cheap in production, also it possesses very good sliding properties in relation to the piston skirt and renders long service lives possible. This is achieved inter alia by the tubular piston skirt, preferably of a beryllium-copper alloy, which can be replaced while the carrier can continue in use. This leads to extraordinarily good material exploitation.